Abstract: Regarding fully signalized four-leg roundabouts, a single-approach-entering operation can be safely and efficiently performed. By using a kind of non-optimization methodology, a phase scheme with four entering vehicle phases, four circulating vehicle phases, and four pedestrian phases is established. Four temporal characteristics of right-of-way assignment are extracted from the design of phase scheme, based on which optimal cycle length and green splits can be determined to conditionally satisfy the temporal demands of different road users on right-of-way. Simulation experimental results indicate that the proposed signal timing plans will substantially prevent the test-bed roundabout performance from seriously deteriorating during peak periods. Also, it is recommended to integrate yield rule and traffic signalization at larger roundabouts on a time-of-day basis.

Key words: road engineering, roundabout, traffic signal control, microscopic traffic simulation